The 'tail' evident in lower definition versions appears here to be an effect caused by sunlght reflecting off a ripple in the hide of the the heavy hind quarters. More like a bear at first glance now, though the movements still don't resemble those of a bear.

Between 0:03 and 0:05 you can now clearly see the animal raise it's head to sniff the air before stepping forward to attack. But the lighting patterns on it's back then seem to ripple and flow with an unnatural fluidity and the body shape distorts rapidly as the animal approaches in an almost surreal, gliding motion between 0:05 and 0:08.